read matrix elements from arguments

examples/rank.rs

 use ark_bls12_381::Fr;
+use ark_ff::Field;
 use komodo::linalg::Matrix;
+use rand::{rngs::ThreadRng, Rng};
+
+fn rand<T: Field>(rng: &mut ThreadRng) -> T {
+    let element: u128 = rng.gen();
+    T::from(element)
+}
 
 fn main() {
-    let m = Matrix::from_vec_vec(vec![
-        vec![Fr::from(1), Fr::from(0), Fr::from(0)],
-        vec![Fr::from(0), Fr::from(0), Fr::from(0)],
-        vec![Fr::from(0), Fr::from(0), Fr::from(0)],
-        vec![Fr::from(0), Fr::from(0), Fr::from(0)],
-        vec![Fr::from(0), Fr::from(0), Fr::from(0)],
-    ])
-    .unwrap();
+    let mut rng = rand::thread_rng();
+
+    let elements = std::env::args()
+        .skip(1)
+        .map(|r| {
+            r.clone()
+                .split(",")
+                .map(|x| {
+                    if x == "-1" {
+                        rand(&mut rng)
+                    } else {
+                        let y: u128 = x.parse().unwrap();
+                        Fr::from(y)
+                    }
+                })
+                .collect::<Vec<_>>()
+        })
+        .collect::<Vec<_>>();
+
+    let m = Matrix::from_vec_vec(elements).unwrap();
 
     eprintln!("{}", m);
+    eprintln!("m: {}", m.height);
+    eprintln!("n: {}", m.width);
     eprintln!("r: {}", m.rank());
 }